GB2160034A - Electrical sockets for use with cathode ray tubes - Google Patents

Abstract

An electrical socket comprises a body (2) receiving a plurality of first contacts/electrodes (11), and an electrical contact/electrode assembly (5) having a plurality of second contacts/electrodes (7,8,9) extending therefrom, said first contacts/electrodes (11) being provided with a slot to receive a respective second contact/electrode. The second contact/electrode is resiliently captured in contact by the first. The contact/electrode assembly (5) is preferably made by the method specified on Application No. 8509033. <IMAGE>

Description

SPECIFICATION Improvements in electrical sockets This invention relates to improvements in electrical sockets and particularly relates to improvements in cathode ray tube sockets.

Examples of prior cathode ray tube sockets can be found, for example, in the specification for United Kingdom Patent No. 2,023,947, and United States Patent Nos. 3,865,452 and 4,119,878.

According to one aspect of the present invention there is provided an electrical socket comprising a body adapted to receive a plurality of first contacts/ electrodes, and an electrical contact/electrode assembly having a plurality of second contacts/electrodes extending therefrom, said first contacts/ electrodes being provided with a slot adapted to receive a respective second contact/electrode.

Advantageously each slot includes a tapered portion where the width of each slot decreases.

Preferably each of the first contacts/electrodes is a resiliently deformable material.

Desirably the tapered portion is provided at a position intermediate the length of the slot, so that the narrowest portion of the slot is provided intermediate the length of the slot.

More desirably the narrowest portion of the slot is provided substantially midway along the length of the slot.

In a preferred construction each slot also includes an insertion portion and a retaining portion.

Each second contact can be inserted into the insertion portion of a respective slot, and then moved through the tapered portion to the retaining portion where it is retained. The retaining portion may be of a width greater than the width of the respective second contact/electrode so that the first contact/electrode exerts a spring force against the respective second contact/electrode thereby holding it in position.

Conveniently at least some of the second contacts/electrodes are provided with a spark gap. For example, the assembly may be a gapped contact/ electrode assembly as described in our copending United Kingdom Patent Application entitled "Method of making a Gapped Contact/Electrode Assembly" of even date.

The body may be provided with a plurality of recesses, each recess receiving one of said first contacts/el ectrodes.

According to another aspect of the invention there is provided a method of forming an electrical socket comprising arranging a body adapted to receive a plurality of first contacts/electrodes, in alignment with an electrical contact/ electrode assembly having a plurality of second contacts/electrodes, and engaging each second contact/ electrode into a slot provided in a respective one of each first contact/electrode.

Advantageously the method includes the step of inserting each second contact/electrode into an insertion portion of the respective first contact and moving each second contact/electrode through the respective slot to a retaining portion of the respective slot which grips the second contact/electrode and holds it in position.

Preferably the method also includes the step of moving each second contact/electrode from the insertion portion to the retaining portion through a tapered portion of a width which is less than the insertion portion and the retaining portion.

Reference is now made to the accompanying drawings, in which: Figure 1 is a perspective exploded view of an electrical socket according to the invention; Figure 2 is a perspective view showing the arrangement of electrical contacts of the electrical socket according to the invention; and Figures 3 and 4 are perspective views of a high voltage cover for the electrical socket according to the invention.

In Figure 1 a CRT (cathode ray tube) socket generally designated 1 comprises a body 2 having a cover 3. Within the body 2 a ledge 4 is provided upon which the lower edge of an electrical contact/ electrode assembly 5 can rest. The assembly 5 is often referred to as an "earth ring". Further details of the contact/electrode assembly can be found in our copending U.K. patent application entitled "Method of Making a Gapped Contact/Electrode Assembly" of even date.

The assembly 5 comprises a generally ringshaped plastics insulation element 6 which supports a plurality of second contacts/electrodes which include contacts 7 and an earth contact 9.

The contacts 7 and 9 project radially from an outer rim 6a of the insulation element 6.

The insulation element 6 has a plurality of apertures 6b and each contact 7 projects through one of the apertures. Each contact 7 is not continuous within each aperture 6b, but is provided with a spark gap 8. A portion 7a of each contact 7, which extends between the spark gap 8 and in the innermost portion of the ring shaped insulation element 6, is electrically connected to a substantially ringshaped electrical conductor (not shown) which is housed within the insulation element 6. In this way the portions 7a are electrically interconnected.

The earth contact 9 does not have a spark gap and is connected to the ring-shaped electrical conductor housed within the insulation element 6.

The body 2 is provided with a plurality of recesses 10 which are shaped to receive a plurality of first contacts/ electrodes including a contact 11.

Although, for clarity, only one contact 11 is shown, each recess 10 receives one of the contacts 11. The first contactslelectrodes also include an earth contact 13 which is received in a shaped recess 12 of the body 2. The contacts 11 and the earth contact 13 are each provided with an elongate slot 14. The slot 14 includes a tapered portion 15, located substantially midway along the length of the slot, where the width of the slot decreases. The material defining the slot 14 in the region of the tapered portion 15 is resiliently deformable so that the width of the tapered portion can be increased by the application of pressure. The slot 14 also includes an insertion portion 15a and a retaining portion 15b which are both of a width greater than the tapered portion 15.

The body 2 is provided with a further recessed portion 17 which is shaped to receive a high voltage contact 19; the contact 19 is provided with an aperture 20 which can receive a lug 21 of the main body 2 in order to secure the contact 19 to the body. A dome shaped portion 22 of the contact 19 extends into an aperture 23 provided in the body 2.

A high voltage earth contact 25 includes a pin portion 26 which extends through a recess 27 of the body 2 and a dome shaped portion 28 which extends into an aperture 29 of the body, the aperture 29 being disposed immediately below the aperture 23.

The contacts 25 and 19 serve the purpose of providing an earth for high voltages. A spark gap is provided between the dome shaped portions 22 and 28 of the contacts 19 and 25, and if the high voltage becomes large enough to jump the gap then the excess current will be drained to earth.

A cover 30 shown in Figures 3 and 4 extends over the high voltage portion of the body 2 in order to isolate it from the rest of the body.

The width of the insertion portion 15a of the slots 14 is large enough to receive the contacts 7 and 9 without any substantial deformation of the contacts 11 and 13. The contacts 7 and 9 are first inserted in the uppermost or insertion portion 15a of the slot 14. The application of force between the second contacts 7 and 9, and the first contacts 11 and 13 causes the second contacts to move downwardly and through the tapered portion 15 and to deform the tapered portion 15 to a width sufficient to permit the first contacts to move past the tapered portion and into the retaining or lowermost portion 15b of the slot 14.

The retaining portion 15b of the slot 14 is narrower than the width of the contacts 7 and 9 so that once the contacts 7 and 9 have been moved into the retaining portion of the slot 14 they are retained there due to the resilient nature of the material of the contacts 11 and 13 exerting a spring force on the contacts 7 and 9. This keeps the contacts 7 and 9 and the contacts 11 and 13 in a positive electrical contact with one another. Figure 2 shows one of the contacts 7 after it has been received in the retaining portion 15b of the slot 14.

It will be appreciated that the contacts 7 and 9 could similarly be moved from the retaining portion 15b, to the insertion portion 15a, upon the application of force sufficient force to deform the material of the second contact 11 or 13.

In use, if the voltage supplied to any of the second contacts 7 from any of the first contacts 11 exceeds a predetermined value then a spark will jump the spark gap 8. This enables the excess current to be drained to earth through the portion 7a of the first contacts 7, through the ring-shaped electrical conductor, through the earth contact 9, from where the current passes to earth through the earth contact 13 of the CRT socket.

In this way, the spark gap device provides a safety mechanism which prevents damage to the CRT.

It will be appreciated that the predetermined value which the current must exceed in order to produce a spark may be varied by varying the size of the spark gap.

The assembly 5 provides protection for relatively low voltages. In order to deal with higher voltages the high voltage contacts 19 and 25 are provided, where there is a larger gap between the dome shaped portions 22 and 28 of each contact.

Claims (14)

1. An electrical socket comprising a body adapted to receive a plurality of first contacts/electrodes, and an electrical contact/electrode assembly having a plurality of second contacts/electrodes extending therefrom, said first contacts/electrodes being provided with a slot adapted to receive a respective second contact/electrode.

2. An electrical socket according to Claim 1 in which each slot includes a tapered portion where the width of each slot decreases.

3. An electrical socket according to Claim 1 or 2 in which each of the first contacts/electrodes is a resiliently deformable material.

4. An electrical socket according to Claim 3 in which the tapered portion is provided at a position intermediate the length of the slot, so that the narrowest length of the slot is provided intermediate the length of the slot.

5. An electrical socket according to Claim 4 in which the narrowest portion is provided substantially midway along the length of the slot.

6. An electrical socket according to any preceding claim in which each slot also includes an insertion portion and a retaining portion.

7. An electrical socket according to Claim 6 in which the retaining portion is of a width greater than the width of the respective second contact/ electrode so that the first contact/electrode exerts a spring force against the respective second contact/ electrode thereby holding it in position.

8. An electrical socket according to any preceding claims in which at least some of the second contacts/electrodes are provided with a spark gap.

9. An electrical socket substantially as herein described with reference to and as shown in the accompanying drawings.

10. A method of forming an electrical socket comprising arranging a body adapted to receive a plurality of first contacts/electrodes, in alignment with an electrical contact/electrode assembly having a plurality of second contacts/ electrodes, and engaging each second contact/electrode into a slot provided in respective one of each first contact/ electrode.

11. A method according to Claim 10 comprising inserting each second contact/electrode in an insertion portion of the respective slot and moving the second contact/electrode through the slot to a retaining portion which grips the second contact/ electrode to hold it in position.

12. A method according to Claim 11 comprising the steps of moving each second contact/electrode from the insertion portion to the retaining portion through a tapered portion of a width less than the insertion portion and the retaining portion.

13. A method according to Claim 10, 11 or 12 in which each first contact/electrode is a resiliently deformable material.

14. A method of forming an electrical socket substantially as herein described with reference to and as shown in the accompanying drawings.